Fucans are polysaccharides originating mainly from the cell walls of shoots of brown algae (Pheophyceae family) belonging to the Ascophyllum, Fucus, Pelvetia and Himmanthali genera. They are also found in some marine animals, such as sea urchins and sea cucumbers. Fucans obtained by extraction from the cell walls of brown algae shoots, also termed fucoidans when in their sulfated form, consist of a heterogeneous population of molecules which comprises principally sulfated L-fucose polymers of average molar mass ranging from 5000 to 800,000 g/mol. These polymers also contain uronic acids. Whilst sulfatation degree, molecular weight, and structure of sugar residues of fucans vary among species, several studies clearly show that brown algae fucans, for example, Ascophyllum nodosum fucans possess a large portion of both α(1→3) and α(1→4) glycosidic bonds.
Fucans have varied biological activities: it was shown that they have anticoagulant and antithrombotic activities (T. Nishino and T. Nagumo, Carbohydr. Res. 229, p. 355-362, (1992); Application EP 0403 377; S. Colliec et al. Thromb. Res. 64, p. 143-154 (1991); S. Soeda et al. Thromb. Res. 72, p. 247-256 (1993); Mauray et al. Thromb. Haemost. (5) 1280-1285 (1995)), they can protect cells against viral infection (M. Baba et al. J. AIDS, 3, p. 493-499, (1990)), they have antiangiogenic (R. Hahnenberger and A. M. Jackobson, Glycoconjugate J., 8, 350-353 (1991)) and anticomplementary (C. Blondin et al., Mol. Immunol., 31, p. 247-253, (1994)) activities. It has also been observed that they can act as modulators of cell adhesion (C. G. Glabe et al., J. Cell Sci., 61, p. 475-490, (1983)), of growth factor release (D. A. Belfort et al., J. Cell. Physiol. 157, p. 184-189, (1993)), of tumor cell's (M. Ellouali et al., Anticancer Res., 13, p. 2011-2020 (1993); D. R. Coombe et al., Int. J. Cancer, 39, pp. 82-90, (1987); D. Riou et al., Anticancer Res., 16, 1213-1218 (1996)) and of vascular smooth muscle cell's proliferation (Logeart et al., Eur. J. Cell. Biol., 74, pp. 376-384 (1997)), and can block spermatozoid/ovule interactions in various species (M. C. Mahony et al., Contraception; 48, p. 277-289, (1993)).
Galactans are other polysaccharides originating mainly from the cell walls of red algae (Redphyceae family). The most abundant galactans found in the red algae are carrageenans and agarans. These polysaccharides play a significant physiological role in the resistance of mechanical stress, hydration, and in both the ionic and the osmotic regulation required within marine environments. Raw galactans are obtained by extraction from the cell walls of red algae shoots, and consist of a heterogeneous population of molecules which comprises mainly sulfated beta-D-galactose, xylose and galactose polymers of average molar mass ranging from 50,000 to 800,000 g/mol.
Galactans have varied known biological activities: They have anticoagulant (Melo et al., J. Biol. Chem. 279:20824-35(2004); Pereira et al., 1999; Facia et al., J. Biol. Chem. 275:29299-307 (2000)) and antiviral activities (Duarte et al., Carbohydr Res. 339:335-47(2004); Huleihel et al., Appl Spectrosc. 57:390-5. (2003); Carlucci et al., Planta Med. 63:429-32 (1997)). It has also been observed that they can act as modulators of proliferation of tumor cells (Zhou et al., Pharmacol. Res. 50:47-53 (2004); Geresh et al J Biochem Biophys Methods. 50:179-87 (2002)).
Processes for obtaining fucans and galactans from a plurality of species have been summarized in Tables 1 and 2, respectively. Generally, brown algae are good sources of fucans while red algae are good sources of galactans.
TABLE 1BROWN ALGAE AS SOURCES OF SULFATED-FUCANS AND KNOWNPROCESSES FOR THEIR OBTENTIONSpeciesReferencesAscophyllum nodosumMarais and Joseleau (Carbohydr. Res 336: 155-159;2001), Mabeau et al. Phytochemistry 29:2441-2445; 1990), Pereira et al. (J. Biol. Chem274(12): 7656-7667; 1999), Tissot et al. (Biochim.Biophys. Acta 165(1-2): 5-16; 2003)Fucus sp.Chevolot et al. (Carbohydr. Res. 330(4): 529-535;2001), Bilan et al. (Carbohydr. Res. 337(8): 719-730; 2002)),Bilan et al. (Carbohydr. Res. 339(3):511-517; 2004), Ruperez et al. (J. Agric. FoodChem. 50(4): 840-845; 2002Stichopus japonicusKariya et al. (Carbohydr. Res. 339(7): 1339-1346; 2004)Sargassum sp.Duarte et al. (Carbohydr. Res. 333(4): 282-293;2001), Zhu et al. (Biochem. Cell Biol. 81(1): 25-33;2003), Zhuang et al. (Biosci. Biotechnol. Biochem.59(4): 563-567; 1995), Nagaoka et al. (Glycoconj.J. 16: 19-26; 1999)Padina gymnosporaAndrade et al. (J. Struct. Biol. 145(3): 216-225;2004)Adenocystis utricularisPonce et al. (carbohydr. Res 338(2): 153-165:2003)CladosiphonSakai et al. (Mar. Biotechnol. 5(6): 536-544; 2003),okamuranusNagaoka et al. (Glycoconj. J. 16: 19-26; 1999)Kjellmaniella crassifoliaSakai et al. (Mar. Biotechnol. 4(4): 399-405; 2002),Nagaoka et al. (Glycoconj. J. 16: 19-26; 1999)Pelvetia canaliculataColliec etal. (Phytochemistry 35: 697-700; 1991)Ecklonia kuromeNishino et al. (Carbohydr. Res. 211(1): 77-90;1991)Chorda filumChizhov et al. (Carbohydr. Res. 320(1-2): 108-119;1999)Undaria pinnatifidaLee et al. (Chem. Pharm. Bull. 52(9): 1091-1094;2004Laminaria japonicaZvyagiintseva et al. (Comp. Bichem. Physiol. C.Toxicol. Pharmacol. 126(3): 209-215; 2000)
TABLE 2RED ALGAE AS SOURCES OF GALACTANS ANDKNOWN PROCESSES FOR THEIR OBTENTIONSpeciesreferencesAsparagopsis sp.Haslin et al. (Planta Med. 67(4): 301-305; 2001)BostrychiaDuarte et al. (Phytomedicine 8(1): 53-58; 2001)montagneiCorallina sp.Usov et al. (Carbohydr. Res. 303(1): 93-102;1997), Cases et al. (Int. J. Biol. Macromol. 16(2):93-97; 1994)Polysiphonia lanosaBatey and Survey (Carbohydr. Res. 43(1): 133-43;1975)Gracilaria sp.Marinho-Soriano and Bourret (Bioresour. Technol.96(3): 379-382; 2005), Freile-Pelegrin and Murano(Bioresour. Technol. 96(3): 295-302; 2005)AcanthophoraDuarte et al. (Carbohydr. Res. 339(2): 335-347;spicifer2004)GeorgiellaKolander and Matulewicz (Carbohydr. Res. 337(1):confluens57-68; 2002)Laurencia coronusUsov et Elashvili (Bioorg. Khim 23(6): 505-511;1997)PorphyraZhang et al. (Carbohydr. Res. 339(1): 105-111;haitanensis2004)BotryocladiaFarias et al. (Thromb. Haemost. 86(6): 1540-1546;occidentalis2001), Farias et al. (J. Biol. Chem. 275(38):29299-29307; 2000)CryptopleuraCarlucci et al. (Planta Med. 63(5): 429-432; 1997)ramosaChondrus ocellatusZhou et al. (Pharmacol. Res. 50(1): 47-53; 2004)GymnogongrusEstevez et al. (Carbohydr. Res. 331(1): 27-41;tolulosus2001)PhacelocarpusLiao et al. (Carbohydr. Res; 296: 237-247; 1996)peperocarpos
Human epithelium plays an essential role in the equilibrium and repair of connective tissues. It is in particular responsible for renewing extracellular matrix (ECM), and in return its functions are modified by the substances present in this matrix.
In particular, in the process of tissue remodeling and healing which intervene after an injury, the connective tissue is the context for constant exchanges between all the cells involved in this process. These exchanges take place in particular via cytokines or soluble mediators which are transmitted through the ECM.
For example, in the covering connective tissues such as the cutaneous tissues, the healing process begins after the formation of a provisional matrix (red thrombus), with the recruitment of inflammatory cells (leukocytes, macrophages and polymorphonuclear cells), which initiate a phase of destruction of the lesioned tissue.
These inflammatory cells participate in the destruction by secreting matrix proteinases such as collagenase (MMP8), leukocytic or neutrophil elastase or cathepsin G, by liberating cytokines, and in particular interleukin-1 (IL-1), which stimulate the proliferation and migration of fibroblasts and of epithelial cells, and the expression, by these cells, of certain metalloproteinases such as interstitial collagenase (MMP1) or gelatinase B (MMP9).
This destruction phase, which begins very soon after the injury, ends when the epithelium and its basement membrane have been reconstituted.
It is followed by repair and resolution phases in which the fibroblasts reconstruct and reorganize the collagen framework; the expression by the fibroblasts of gelatinase A (MMP2) is in particular observed, matrix metalloproteinase actively participating in all the tissue remodeling phenomena.
Repercussion of UV exposure on the skin microcapillary integrity: The cutaneous layer is the primary external barrier protecting the body from harm as a result of invading foreign particles. In order to adequately perform its function, the skin has been endowed with a range of endogenous surveillance systems. Following tissue damage, free radicals are released with active cytokines to counteract these non-self particles. Subsequently, enzymatic activities proceed to dismantle damaged components such as cell bodies and fibrillar components of the ECM. This occurs before repair processes establish and are able to promote cellular proliferation and biosynthetic activity of the ECM's components.
At the microscopic level, the skin may be viewed as a highly complex arrangement of diversified cell types which are embedded within the ECM. In addition to serving as a structural scaffold, the ECM functions as a highway providing the means for cell movement, migration and differentiation. It also functions as a signal transduction pathway through which chemical mediators are able to travel between individual cells and the superposed skin layers. To a certain extent, the skin's ECM may be conceptualized as a loose interlaced cotton weave into which cells are nested and able to interact with one another and their surrounding environment.
The ECM appears as a complex array of macromolecules and fibrillar components. These components are fashioned with various types of collagen fibers, elastin fibers, glycosaminoglycans and glycoproteins. The ECM is both produced and organized by its resident cells; mainly the keratinocytes and fibroblasts. This amalgamated connective tissue is responsible for the firmness, elasticity as well as the overall integrity of the skin. Despite its highly intricate fibrillar composition, the ECM remains a dynamic structure. As such, it must be involved in morphogenesis and tissue repair, thus supporting cell proliferation and macromolecular remodelling. The plasticity of the ECM can further be demonstrated in its role in sensing external mechanical forces.
It has been suggested that the application of tensile, gravitational force and stretching forces to the skin trigger a mechanochemical signal transduction (mechanosensing) involving the direct ECM-cell and/or cell-cell interactions (Silver F H, Siperko L M. Crit Rev Biomed Eng. 2003; 31(4):255-331). Specifically, the ECM network acts as a sensor that informs skin cells on how to adapt to dynamic environmental conditions. Through downstream signal transduction, the skin's ECM may also influence other tissues through their response to external stimuli (Eckes B, Krieg T. Clin Exp Rheumatol. 2004 January-February; 22(3 Suppl 33):S73-6). For instance, the mechanical forces imposed by a tridimensional collagen network switch on “mechanical-responsive genes” that favour a synthetic phenotype (Kessler D, Dethlefsen S, Haase I, Plomann M, Hirche F, Krieg T, Eckes B. J Biol. Chem. 2001 Sep. 28; 276(39):36575-85). This illustrates the ability of the ECM to support both a biochemical role and an obvious physical function as a home for resident cells. As a result of its intimate interaction with the external environment, the ECM and its associated structures are vulnerable to the continuous barrage of external insults. Ultimately, the repeated effects of these insults may affect the skin's health and appearance.
Chronological and actinic aging of the skin: Aging is a multifactorial phenomenon. The aging of the skin is mainly the result of one's genetic predisposition (known as chronological aging) and one's physiological reaction to environmental stresses (known as actinic aging). Chronological aging is largely genetically driven and appears to be mainly a reduction in anti-oxidant production (Finkel T, Holbrook N. J. Nature. 2000 Nov. 9; (408):239-247), cellular senescence and a general lowering of anabolic activities (Jenkins G. Mech Ageing Dev. 2002 April; 123(7):801-10). Actinic aging seems to be skin specific and is defined as the effect of the external environment on the skin's biological response. The skin response to actinic aging, also referred to as photo-damage, is typically associated with a lack of normal hydration, apparition of telangiectasia, sagging of the skin and the appearance of fine line and wrinkles.
Environmental insults, such as UV and/or polluting deleterious chemicals found in the atmosphere are typically encountered by keratinocytes of the epidermis which are located at the outmost peripheral level of the skin. The reaction of keratinocytes to the environmental stimuli triggers a cascade of reactions where the acquisition of the initial signal is passed on from cell to cell through a mechanism of biochemical interpretations. As a result, the ensuing biological response may be amplified and propagated to other layers of the skin. This cascade of biochemical reactions, especially upon UV exposure, is directly correlated to a number of histological damages that accumulate to provoke the appearance of signs of actinic aging.
UV irradiation has been shown to have pleiotropic effects at the skin level causing DNA lesions, cellular apoptosis, immunosuppression and inflammation/erythema (Soter N A. Semin Dermatol. 1990 March; 9(1):11-5, Matsumura Y, Ananthaswamy H N. Expert Rev Mol. Med. 2002 Dec. 2; 2002:1-22). With respect to actinic skin aging—or photo-damage—the increase in matrix metalloproteinase (MMP) activation and expression is the most recognized degradation pathway induced as a result of the skin exposure to UV (Fisher G J. CUTIS. 2005 February; (75):5-9). It has been suggested that the proteolytic action of MMP causes the breakdown of collagen fibers in the ECM and that the histological damages which ensues eventually leads to the appearance of a photo-damaged phenotype (Fisher G J, Wang Z Q, Datta S C, Varani J, Kang S, Voorhees J J. New-England Journal of Medicine. 1997; 337:1419-1428; Fisher G J, Kang S, Varani J, Bata-Csorgo Z, Wan Y, Datta S, Voorhees J J. Arch Dermatol. 2002 November; 138(11):1462-70; Brennan M, Bhatti H, Nerusu K C, Bhagavathula N, Kang S, Fisher G J, Varani J, Voorhees J J. Matrix Photochemistry and Photobiology. 2003; 78(1):43-48). Furthermore, it is suggested that the reduction in the ability of fibroblasts to synthesize collagen is reduced in photo-damaged skin as a result of a decreased cell-ECM mechanical tension (Varani J, Schuger L, Dame M K, Leonard C, Fligiel S E, Kang S, Fisher G J, Voorghees J J. J Invest Dermatol. 2004 June; 122(6):1471-9).
Alteration to the tridimensional organization of the skin's ECM is undoubtedly among the most significant and apparent molecular changes during actinic aging. This microscopic modification ultimately results in the macroscopic appearance of cutaneous aging. Those changes triggered during actinic aging involve the release of biochemical mediators that have pleiotropic actions in skin structures. It is known that the phenomena of microcapillary dilation and increased permeability figure among the early cutaneous responses upon UV exposure.
Roles of VEGF and PGE2 in the conformational changes of skin microcapillaries: The reactions of skin microcapillary dilation and hyperpermeability are characteristic of an excessive UV exposure and lead to the inflammation of the skin (Matsumura Y, Ananthaswamy H N. Toxicol Appl Pharmacol. 2004 Mar. 15; 195(3):298-308). Microcapillary integrity is influenced by biochemical mediators such as cytokines and other specific growth factors found in the skin. Among these, the pro-inflammatory prostaglandin E2 (PGE2) plays a central role in the skin's response to stress as its expression is readily triggered by inflammatory stimuli (Kabashima K, Miyachi Y. Journal of Dermatological Science. 2004; 34:177-184; Lee J L, Mukhtar H, Bickers D R, Kopelovich L, Altar M. Tox Appli Pharmacol. 2003; (192):294-306; Bachelor M A, Bowden G T. Seminars in Cancer Biology. 2004; 14:131-138). The expression of PGE2 is upregulated in skin following exposure to UV (Hruza L L, Pentland A P. J Invest Dermatol. 1993 January; 100(1):35S-41S) whereby it acts upon specific cell receptors and mediates microcapillary dilation (Lee J L, Mukhtar H, Bickers D R, Kopelovich L, Altar M. Tox Appli Pharmacol. 2003; (192):294-306). The UV-induced increase in PGE2 may be achieved through multiple signal transduction pathways (Ashida M, Bito T, Budiyanto A, Ichihashi M, Ueda M. Experimental Dermatology. 2003; 12:445-452). Furthermore, dilated microcapillaries are also more susceptible to the leakage of leukocytes into the ECM where they can release pro-inflammatory cytokines, growth factors and degradation enzymes. This can be demonstrated in the inflammatory skin condition rosacea, which is characterized by the presence of dilated vessels (Van Zuuren E, Graber M, Hollis S, Chaudhry M, Gupta A, Gover M. Cochrane Database Syst Rev. 2005 Jul. 20; (3):CD003262) and a collapsed EGM structure (Crawford G H, Pelle M T, James W D. J AM Acad Dermatol. 2004 September; 51 (3):327-41).
The Vascular Endothelial Growth Factor (VEGF) is also a factor known to be induced in keratinocytes and fibroblasts by a specific range of effectors such as tissue hypoxia (Detmar M, Brown L F, Berse B. Jackman R W, Elicker B M, Dvorak H F, Claffey K P. J Invest Dermatol. 1997 March; 108(3):263-8.), pro-inflammatory cytokines (Trompezinski S, Berthier-Vergnes O, Denis A, Schmitt D, Viac J. Exp Dermatol. 2004 February; 13(2):98-105), nitric oxide (Frank et al., 1999), toxins (Deasi A, Lankford H A, Warren J S. Inflammation. 2000 February; 24(1):1-9) and upon exposure to UV. VEGF is a regulator of angiogenesis (the formation of new blood vessels) in inflammatory conditions (Detmar M, Brown L F, Schon M P, Elicker B M, Velasco P, Richard L, Fukurama D, Monsky W, Claffey K P, Jain R K. J Invest Dermatol. 1998 July; 111(1):1-6). For instance, the expression of this growth factor has been shown to be upregulated in psoriasis (Detmar, 1994) as well as in rosacea (Lachgar S, Charveron M, Gall Y, Bonafe J L. Dermatology. 1999; 199 Suppl 1:25-7). Keratinocytes represent an important source of VEGF (Ballaun C, Weninger W, Uthman A, Weich H, Tschachler. J Invest Dermatol. 1995 January; 104(1):7-10). VEGF expression in these cells may be induced via both UVA and UVB and it has been suggested that this induction mechanism differs according to the specific type of stimuli (Gille J, Reisinger K, Asbe-Volikopf A, Hardt-Weinelt K, Kaufmann R. J Invest Dermatol. 2000 July; 115(1):30-6; Kosmadaki M G, Yaar M, Arble B L, Gilchrest B A. FASEB J. 2003 March; 17(3):466-8; Longuet-Perret I, Schmitt D, Viac J. Br J. Dermatol. 1998 February; 138(2):221-4). VEGF affects a host of parameters of skin microvasculature; the most prominent being the increase in permeability of microcapillaries (Dvorak H F, Brown L F, Dvorak A M. Am J. Pathol. 1995 May; 146(5):1029-39). It has been postulated that VEGF (first known as the Vascular Permeability Factor) induces microcapillary hyperpermeability through the loosening of endothelial cell-cell interaction creating microbreaches through which leukocytes (neutrophils) and plasma exudate (Harhaj N S, Antonetti D A. Int J Biochem Cell Biol. 2004 July; 36(7):1206-1237).
Additionally, VEGF secretion by the fibroblasts has been shown not only to be upregulated by UV, but also by PGE2 itself (Trompezinski S, Pernet I, Schmitt D, Viae J. Inflamm Res. 2001; (50):422-427). The autocrine/paracrine effect of PGE2 on VEGF secretion by skin cells exemplifies the complex cell-cell communication which exists under stressful conditions. With the aging process, positive regulation of PGE2 on VEGF secretion becomes even more strategic as UV-induced PGE2 production in the skin increases as one ages (Seo J Y, Kim E K, Lee S H, Park K C, Kim K H, Eun H C, Chung J H. Mechanisms of Ageing and Development. 2003; (124): 903-910). This observation further illustrates the cross-talks that occur between the biochemical pathways involved in both chronological aging and actinic aging. A synergistic superimposition of these two aging modes would accelerate the loss of integrity of skin microcapillaries (dilation and hyperpermeability) and exacerbate leukocyte efflux.
Neutrophils (a subset of leukocytes also referred to as polymorphonuclear cells) efflux towards the ECM as a result of microcapillary dilation and hyperpermeability. Evolving scientific knowledge provides increasing support for the importance of dermo-epidermal infiltrating neutrophils as effectors in the process of photo-damage. Neutrophils represent important cellular sources of not only elastase but also of other known ECM-degradation enzymes such as the metalloproteinases (MMP-1, MMP-8 and MMP-9; Rijken F, Kiekens R C M, Bruijnzeel P L B. British Journal Dermatology. 2005 February; 152(2):321-8). Most of the emphasis within the scientific community focused around MMPs and their action in causing the breakdown of collagen fibers and other ECM macromolecules. However, the action of a specific catabolic enzyme, elastase, may also impose significant consequences to the integrity of the ECM and its components. Elastase targets specific molecular substrates (elastin fibers) that may differ from those attacked by MMP (mainly collagen fibers), however, the outcome is similar and translates into the comparable disorganisation of the skin ECM.
Human leukocyte elastase (HLE), a broad spectrum serine protease of 30 kDa, is a specific elastolytic enzyme that is involved in the turnover of elastic fibers and the remodelling of the ECM. Elastin fibers are mostly responsible for the resiliency of the skin's ECM. Even though elastin fibers represent less than 2% of the total dry weight of the skin (in comparison, collagen fibers comprise more than 70% of total skin dry weight), they intermingle in functional interactions with other fibrillar macromolecules and provide the visco-elastic properties required for normal skin functions.
Released from a signal source, cytokines initiate the efflux of neutrophils toward the ECM, seemingly mimicking an inflammatory reaction. Neutrophils gain access to the signal source by migrating through the connective tissue thereby destroying encountered fibrillar components. Once in the connective tissue, neutrophils cells actively continue the secretion of degradation enzymes thereby continuing their mission by breaking down elastic fibers of the ECM. Excessive proteolytic activity of proteolytic enzymes such as MMPs and neutrophil elastase is known to be associated with structural alteration of the tridimensional organization of the ECM. Ultimately, these histological modification deleterious changes will translate into macroscopic symptoms degeneration deterioration and become visible in the form of fine lines and wrinkles; hallmarks of skin aging.
The importance of elastic fibers for the maintenance of skin resiliency and elasticity is well exemplified in the many skin disorders in which the integrity of elastin network is affected (Lewis K G, Bercovitch L, Dill S W, Robinson-Bostom L. J Am Acad Dermatol. 2004 July; 51(1):1-21; Lewis K G, Bercovitch L, Dill S W, Robinson-Bostom L. J Am Acad Dermatol. 2004 August; 51(2): 165-85).
The integrity of the ECM and its dynamic interactions with skin cells is of primary importance in tissue repair (Midwood K S, Williams L V, Schwarzbauer J E. Int J Biochem Cell Biol. 2004 Juhn; 36(6):1031-7).
A relationship has been established between UV exposure, up-regulation of VEGF, exudation of elastase-producing neutrophils in the skin, disorganisation of the elastin compartment of the ECM and the appearance photo-damage (Yano K, Kadoya K, Kajiya K, Hong Y K, Detmar M. Br J. Dermatol. 2005 January; 152(1):115-21). The same research group (Yano K, Kajiya K, Detmar M. A novel mechanism of cutaneous photo-damage mediated by angiogenesis and inhibitory effects of chlorella extract on UV-induced angiogenesis. 23rd IFSCC Congress. 2004; 46-51) has shown that a Chlorella extract (a green algae extract) increases trombospondin-1 (TSP-1) expression in UVB irradiated keratinocytes and prevents UVB-induced predominant expression of VEGF against TSP-1 in vitro.
Cellular and molecular mechanisms triggered by UV and leading to the appearance of clinical signs of actinic aging may reflect a confused inflammatory and repair elicited response of the skin in reaction to environmental aggressions.
Thus, some pathologies are accompanied by a chronic inflammatory state of the connective tissue in which the balance between the destruction, repair and resolution phases is upset which leads to defective reconstruction of the lesioned tissue.
With this aim, the inventors have studied the action of various polysaccharide compositions. It is known that specific polysaccharide compositions, such as glycosaminoglycans, participate in the composition of the proteoglycans present at the cell/extracellular matrix interface, and play a role in regulating cell functions. It is also known that glycosaminoglycans in a soluble form, for example heparin or dextran derivatives, can modify cell functions via their interaction with various components of the ECM.
Ferrao and Mason (Biochem. Biophys. Acta. 1180, 225-230, (1993)) have studied the action of various polysaccharides on human dermal fibroblast proliferation, and indicated that at concentrations of about 100 μg/ml, heparin, heparan sulfate, pentosan polysulfate and a fucoidan inhibit this proliferation, whereas chondroitin sulfate, dermatan sulfate and hyaluronate have no effect. It is indicated that the inhibitory effect on proliferation leads to a stimulation of type I collagen synthesis. Conversely, an inhibition of collagen I synthesis is observed when the polysaccharides are added to cultures which have reached confluence.
Berteau and Mulloy (Glycobiology 13(6): 29R-40R, 2003) have made a review on fucans, wherein it is said that, like heparin, they have anti-proliferative effects on vascular smooth muscle cells and on fibroblasts, in addition to an anti-coagulant effect. Nothing is disclosed on the activity of fucans on VEGF or on inflammation mediators, except for TNF-alpha.
Matsumoto et al. (Clin. Exp. Immunol 136(3): 432-439, 2004) showed that oral ingestion of fucans from Cladosiphon okamuranus Tokida (0.05% w/w with food) inhibits the release of Interferon gamma and IL-6 by colonic lamina propria cells. They propose fucans as dietary supplement for treating patients with inflammatory bowel disease.
Zhang et al. (Zhang Q, Li N. Qi H Xu Z. Li Z Phytother Res. 2005 January; 19(1):50-3) reported that elevated urinary protein excretion and plasma creatinine due to the induction of Heymann nephritis were significantly reduced by fucoidan oral administration at doses of 100 and 200 mg/kg, daily. The renoprotective effect of fucoidan on active Heymann nephritis is a good indication of its bioavailability after oral administration.
Li et al (Li N., Zhang Q, Song J. Food Chem. Toxicol. 2005 March; 43(3):421-6) investigate the acute and subchronic (6 months) toxicity of fucoidan extracted from Laminaria japonica in Wistar rats. Fucoidans did not show significant toxicological changes when 300 mg/kg body weight per day of fucoidan was orally administered. However, the clotting time was significantly prolonged when the dose was increased to 900 and 2500 mg/kg body weight per day. Besides this, no other signs of toxicity were observed. Based on these results, it can be concluded that no adverse effect level of fucoidan from L. japonica is observed at or below 300 mg/kg body weight per day.
Granert et al. (J. Clin. Invest. 93: 929-936, 1994) disclose that fucans, administered i.v. (10 mg/Kg body weight) reduce the accumulation of leukocytes and plasma proteins in the CSF of rabbits intrathecally challenged with pneumococcal antigen. They also show that fucans inhibit leukocyte recruitment into an inflamed tissue site (rabbit skin) thus suggesting that fucans may be effective when administered in situ or at a distance from the inflamed site.
Preobrazhenskaya et al. (Biochem. Mol. Biol. Int. 43(2): 443-451, 1997) show that neutrophil recruitment into an inflammatory site (rat peritoneum) is reduced by fucans administered i.v. (0.8 mg). The anti-extravasation effect is quite remarkable but has a short duration.
One of the drawbacks of the use of fucans and galactans is their cytoxicity. Stevan et al (J. Submicrosc. Cytol. Pathol. 33(7): 477-484, 2001) show that fucans, particularly, at a sulfate/sugar ratio of 1.9 and concentration of 2.5 microgram/mL cause toxicity in HeLa cells, as seen from the atypical nuclei, altered cell morphology and impaired cell division.
There is therefore a need to improve fucans compositions to increase their efficacy and decrease their toxicity.
The present invention seeks to meet these needs and other needs.
The present description refers to a number of documents, the content of which is herein incorporated by reference in their entirety.